The water column distributions of the alkaline earth metals strontium (Sr) and barium (Ba) were studied along a transect from Hawaii to Alaska. Despite similarity in the chemical properties of Sr and Ba, we find that changes in their concentrations along the transect are governed by different chemical and biological processes, meaning that these elements can be treated as independent variables in modern and ancient environments. Alaskan margin sediments are a particularly important source of dissolved Ba to the North Pacific, likely through a combination of saline submarine groundwater discharge and reductive dissolution of manganese (Mn) oxides. Abyssal North Pacific sediments are also a source of Ba to the bottom waters but a sink for Sr. We find that over 90 % of the water column variability in Sr concentrations is driven by precipitation and dissolution of the celestine (SrSO4) skeletons of Acantharia. However, the high Ba content of Acantharia celestine accounts for only 5–8 % of the global ocean variability in Ba concentrations in the water column. Similarly, the effects of barite (BaSO4) precipitation and/or dissolution on the marine Sr cycle is negligible, accounting for <1 % of the water column concentration structure for Sr and ∼3 % of the sedimentary Sr burial. The Sr-Ba-PO4 concentration distributions in the North Pacific are inconsistent with significant export of barite to the deep ocean and sediment. This suggests most of the barite formed at intermediate depths dissolves at similar horizons to its formation. The Ba content of phytoplankton organic matter is too low to constitute a major source for particulate Ba in the mesopelagic North Pacific, which suggests Ba is concentrated in marine aggregates by heterotrophic micro-organisms.

中文翻译：

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天青石和重晶石在调节东北太平洋锶和钡水柱浓度中的作用


研究了从夏威夷到阿拉斯加的沿样带的碱土金属锶 （Sr） 和钡 （Ba） 的水柱分布。尽管 Sr 和 Ba 的化学性质相似，但我们发现它们沿样带的浓度变化受不同的化学和生物过程控制，这意味着这些元素在现代和古代环境中可以被视为独立变量。阿拉斯加边缘沉积物是北太平洋溶解 Ba 的一个特别重要的来源，可能是通过盐水海底地下水排放和锰 （Mn） 氧化物的还原溶解相结合。深海北太平洋沉积物也是 Ba 到底层水的来源，但也是 Sr 的汇。我们发现，超过 90% 的水柱 Sr 浓度变化是由 Acantharia 的天体 （SrSO4） 骨骼的沉淀和溶解驱动的。然而，棘荚的高 Ba 含量仅占全球海洋水柱中 Ba 浓度变化的 5-8%。同样，重晶石 （BaSO4） 沉淀和/或溶解对海洋 Sr 循环的影响可以忽略不计，占 Sr 水柱浓度结构的 <1 % 和沉积 Sr 埋藏的 ∼3 %。北太平洋的 Sr-Ba-PO4 浓度分布与重晶石向深海和沉积物的大量出口不一致。这表明，在中等深度形成的大部分重晶石在与其形成相似的层位处溶解。浮游植物有机质的 Ba 含量太低，无法构成中上层北太平洋颗粒物 Ba 的主要来源，这表明 Ba 由异养微生物集中在海洋聚集体中。